Fungus-like Protists
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Printed: June 28, 2013
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C ONCEPT
Concept 1. Fungus-like Protists
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Fungus-like Protists
• Describe examples and features of the fungus-like protists.
What’s eating these frog eggs?
The thin filaments growing out of these dead frog eggs look a little like a fungus. Also this mystery organism, like a
fungus, is feeding on decaying matter. However, this is not a fungus. This organism is a type of fungus-like protist,
known as water mold.
Fungus-like Protists
Fungus-like protists share many features with fungi. Like fungi, they are heterotrophs, meaning they must obtain
food outside themselves. They also have cell walls and reproduce by forming spores, just like fungi. Fungus-like
protists usually do not move, but a few develop movement at some point in their lives. Two major types of funguslike protists are slime molds and water molds.
Slime Molds
Slime molds usually measure about one or two centimeters, but a few slime molds are as big as several meters. They
often have bright colors, such as a vibrant yellow (Figure 1.1). Others are brown or white.
Stemonitis is a kind of slime mold which forms small brown bunches on the outside of rotting logs. Physarum
polycephalum lives inside rotting logs and is a gooey mesh of yellow "threads" that are several centimeters long.
Fuligo, sometimes called “vomit mold,” is a yellow slime mold found in decaying wood.
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FIGURE 1.1
An example of a slime mold.
Water Molds
Water molds mostly live in water or moist soil. They can be parasites of plants and animals. They are a common
problem for farmers since they cause a variety of plant diseases. One of the most famous of these diseases was the
fungus that caused the Irish potato famine in the 1800s. At this time, potatoes were the main source of food for many
of the Irish people. The failure of the potato crop meant that many people in Ireland died of starvation or migrated
to other countries.
Vocabulary
• slime mold: Fungus-like protist that grows as slimy masses on decaying matter.
• water mold: Fungus-like protist present in moist soil and water; lives as a parasite or on decaying organisms.
Summary
• Slime molds are fungus-like protists that grow as slimy masses on decaying matter. They are commonly found
on items such as rotting logs.
• Water molds are fungus-like protists present in moist soil and surface water; they live as parasites or on
decaying organisms.
Practice
Use the resources below to answer the questions that follow.
• The Blob: Slime Mold at http://herbarium.usu.edu/fungi/FunFacts/slimemold.htm.
1. Why are slime molds not classified as fungi?
2. What does a slime mold eat?
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Concept 1. Fungus-like Protists
• John Bonner’s Slime Mold Movie at http://www.youtube.com/watch?v=bkVhLJLG7ug (1:42)
MEDIA
Click image to the left for more content.
1. What happens when you separate the cells of a slime mold?
2. Do you think this behavior represents intelligence? Why or why not?
3. Slime molds will form stalks with fruiting bodies.
a. What happens to the cells of the stalk?
b. What happens to the cells of the fruiting body?
c. How is this behavior similar to fungi?
• Introduction to Phytophthora at http://www.youtube.com/watch?v=B5x_DHqVvSs (7:40)
MEDIA
Click image to the left for more content.
1.
2.
3.
4.
What areas of plants can be infected by water molds?
What kind of environment do water molds need to complete their life cycle?
What appears to be the closest relative to water molds?
What are zoospores? What do they enable water molds to do?
Review
1. What are examples of fungus-like protists?
2. How do water molds get their nutrients?
References
1. Courtesy of the National Park Service. Slime mold.. Public Domain
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